350 MPI Horizon Base Timing
#11
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As far as plugs, merc uses the platinum plugs because that’s what gm installs in them before shipping to merc.
The copper MR43LTS (you have vortec heads riight) are cheaper, last long in time because who drives there boat 30k miles anyway ? Platinum good for 70k and higher. Lol.
The LTS come gapped at .044”, therefore not far to bend (close) to .035”-.040”. Less current going thru the cap/rotor will give better chance of not running into cap problems.
The copper MR43LTS (you have vortec heads riight) are cheaper, last long in time because who drives there boat 30k miles anyway ? Platinum good for 70k and higher. Lol.
The LTS come gapped at .044”, therefore not far to bend (close) to .035”-.040”. Less current going thru the cap/rotor will give better chance of not running into cap problems.
#12
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Vortec heads used from approx 1996 and up. Easy to identify. Intake is held down with 8 bolts (4 per cyl head) at a straight down angle. Earlier heads had 12 bolts (6 per head)) at angles holding intake to the heads. Those used MR43T plugs.
1st pic Vortec (note straight up and down bolt holes. Their are none in middle positions unlike earlier heads)
![](https://cimg0.ibsrv.net/gimg/www.offshoreonly.com-vbulletin/400x186/image_3b2d4f9b50363ffd4d38213770a3003bea8e5283.jpeg)
2nd pic earlier sbc heads
![](https://cimg8.ibsrv.net/gimg/www.offshoreonly.com-vbulletin/600x293/image_537411b60f8d11bccab81c6e5150dad02b365f1c.jpeg)
1st pic Vortec (note straight up and down bolt holes. Their are none in middle positions unlike earlier heads)
![](https://cimg0.ibsrv.net/gimg/www.offshoreonly.com-vbulletin/400x186/image_3b2d4f9b50363ffd4d38213770a3003bea8e5283.jpeg)
2nd pic earlier sbc heads
![](https://cimg8.ibsrv.net/gimg/www.offshoreonly.com-vbulletin/600x293/image_537411b60f8d11bccab81c6e5150dad02b365f1c.jpeg)
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Basketcase (05-10-2022)
#13
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Playing around with this, I discovered that it is quite a bit off. So much so, that I don't think the housing will rotate far enough without interference. Does this mean that its off a tooth?
![](https://cimg4.ibsrv.net/gimg/www.offshoreonly.com-vbulletin/781x1041/pxl_20220510_160354897_38ada5605974594490762d9878a2a042721a2b46.jpg)
![](https://cimg6.ibsrv.net/gimg/www.offshoreonly.com-vbulletin/781x1041/pxl_20220510_155133102_night_3bffcd5098825015940b13850b1c79389eceab77.jpg)
![](https://cimg4.ibsrv.net/gimg/www.offshoreonly.com-vbulletin/781x1041/pxl_20220510_160354897_38ada5605974594490762d9878a2a042721a2b46.jpg)
![](https://cimg6.ibsrv.net/gimg/www.offshoreonly.com-vbulletin/781x1041/pxl_20220510_155133102_night_3bffcd5098825015940b13850b1c79389eceab77.jpg)
#14
Registered
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If turning dist and there is interference, dist is prob off a tooth. Prob someone who didn’t move oil pump pushrod a hair (need long flat blade screwdiver) and just dropped it back in.
You ever put a chevy dist back in ? If so, this is piece of cake.
You know the history on this ?
You ever put a chevy dist back in ? If so, this is piece of cake.
You know the history on this ?
Last edited by SB; 05-10-2022 at 11:46 AM.
#15
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If turning dist and there is interference, dist is prob off a tooth. Prob someone who didn’t move oil pump pushrod a hair (need long flat blade screwdiver) and just dropped it back in.
You ever put a chevy dist back in ? If so, this is piece of cake.
You know the history on this ?
You ever put a chevy dist back in ? If so, this is piece of cake.
You know the history on this ?
#16
Registered
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Lol.
Any ways. Dist is easy. Loosen clamp first and see if it turns enough. Recheck alignment when you tighten clamp. It can move a few degrees as the dist and cam gear are helical.
Any ways. Dist is easy. Loosen clamp first and see if it turns enough. Recheck alignment when you tighten clamp. It can move a few degrees as the dist and cam gear are helical.
#17
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I'll give it a shot. just looking at it, it looks like the housing will hit the intake manifold before it gets to the exact right location. I bet I can get it close. One fun thing would be if I had to remove it. I may or may not have enough room to get it out of the boat. Perhaps I could pull it up, rotate it, drop it, and turn the engine by hand to line up the oil pump?
#18
Registered
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No no no. I’ll give you my cell in a pm. I mumble so put your good ears on. Leave engine at tdc. It’s easy.
#20
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On this, you don't need too. There is a little pointer if you will on the distr that the rotor will point too. It's about an inch or so up from where his rotor is in that pic. And by his pic, his dampener is at TDC.